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Topic: Thermometers (Read 7346 times)

So, read a lot on the other thermometer topics in this forum, and I still have a couple of questions.

I fall into the "OMG why do I have so many thermometers that disagree with each other camp" (2 dial type long stem "brewing" thermometers, 1 floating dairy thermo, several small kitch thermos, an alchohol lab thermo, and a thermocouple)

After calibration at 0, none of them seem to line up at mash temperatures. Some are off by as much as 20°F. I know the common theme is, if youa re brewing good beer, don't fret. I love this advice, but my beer is not as good as I'd like it, and I suspect my mash efficiency is at least partially to blame.

So why don't more brewers rely on something like a glass lab thermometer? (Not Mercury filled) They seem to have some of the lowest errors and highest resolutions available for relatively cheap, and if you don't drop them, they should last forever. Why isn't this the standard in brewing?

Also, as a side note, where does one get a hydrometer calibrated for mash temp? I have a 60°F hydrometer, but I feel like the "conversions" to adjust my first runnings to a real SG don't always hold up.

I think the thing alot of folks are looking for in a thermo is quick reading and the glass types just aren't that quick.

on the hydro temp correction you are right. the conversion tables aren't super accurate when converting from a really high temp. no answer there except to cool the sample before reading or get a refractometer

For what it's worth, once you know what your hydrometer reads at mash temp for a couple target gravities, you should be able to use it at those temperatures. At least until you brew a different size beer.

I think the thing alot of folks are looking for in a thermo is quick reading and the glass types just aren't that quick.

Is there a step somewhere I'm not doing where the extra 15-20 seconds is critical? Seems like it takes that long for my 2-metal thermos to read. If you just left a glass thermometer in whatever you were measuring, you would get reasonably reliable and rapid reads, right? Am I missing some critical piece of experience?

For what it's worth, once you know what your hydrometer reads at mash temp for a couple target gravities, you should be able to use it at those temperatures. At least until you brew a different size beer.

True, but if I'm trying to do things like measure first runnings versus second runnings, that will never be comparable to an OG after the boil (assuming I batch sparge). So it sounds like, just cool some of the runnings down, measure them, and then toss them back into the mash. And I suppose the sensible thing to do would be to keep a log of comparable gravities at mash temp and rt, then back-calculate that conversion for my own hydrometers. Thanks for the idea!

I bought a Thermapen after wasting money on at least 5 cheapo thermometers. It's definitely one of the best brewing tools I own. I'm buying one for my father-in-law for Christmas. Do yourself the favor get a decent thermometer. I promise you won't be sorry.

If you are looking to get your pre boil gravity readings I would highly suggest getting a refractometer with ATC. That will be so much easier than slowing down your day waiting for a hydro sample to cool. You can pick one up on eBay for under $30 including sipping.

+1 to a Thermopen. They are pricey but are very accurate and quick. They are standard in the professional cooking world. Once you get one you will understand the cost. The are built very well.

Thermoworks also sells a type-k thermocouple version, which can accept various probes including a waterproof wire probe. I use this and leave it in the mash tun and HLT for getting a constant read on temperature.

If you are looking to get your pre boil gravity readings I would highly suggest getting a refractometer with ATC. That will be so much easier than slowing down your day waiting for a hydro sample to cool. You can pick one up on eBay for under $30 including sipping.

Good luck!

Refractometers are soooo much better than hydrometers for checking gravity on your brewday.

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